This invention relates to inductor generators for welding in each of which a plurality of electrogenerator elements are formed within a single generator so that a plurality of welders can simultaneously carry out welding work. More particularly, the invention relates to an inductor generator for welding of the above stated character in which, when respectively different outputs are being derived from the generator elements, inadvertent fluctuations of the previously set output values arising from magnetic influence mutually between the generator elements are effectively prevented.
Heretofore, in the case where a plurality of workers were to carry out welding work simultaneously at an outdoor work site, it has been the common practice to use engine-driven welding machines or units of the same number as the workers. By this practice, however, since these welding units are operated simultaneously, they produce much noise, vibration, and exhaust gas and, in many cases have been a source of public nuisance.
On the other hand, for the same purpose, generator power units of the type in which a plurality of generators are coaxially coupled to a single engine, those of the type in which a plurality of generators are driven by a single engine by belt drive, and other like systems have recently been proposed. However, the dimension in the engine axial direction in the former type and that in the width direction in the second type become enormous, and the entire machine becomes large, whereby not only are the portability and mobility greatly impaired for outdoor work, but, if the plurality of generators are to be accommodated in one and the same housing structure, the construction will become complicated, and repairs and maintenance will become troublesome.
Accordingly, one possible arrangement of an inductor generator system is that wherein, in a single generator: a plurality of generator elements are combined, each generator element having a field winding and an armature winding and further being provided with an excitation winding for self-excitation, the electromotive force of each excitation winding being applied by way of a rectifier and a variable resistor to the field winding, and the output of each armature winding is applied via a rectifier across a welding rod and the corresponding base or parent metal.
However, the generator elements have a variety of mutual effects and particularly impart magnetic influences on each other. For this reason, when the output of any one of the generator elements is caused to vary, the field currents and, further, the outputs of the armature windings of the other generator elements fluctuate in spite of the constant values of their respective variable resistors. This has been a problem in the prior art.
Accordingly, an inductor generator system in which, as disclosed in the specification of Japanese Utility Model Application No. 179260/1977, as a separate excitation type: a single yoke is so formed that its width is made narrow in the radial direction at positions spaced at n equal intervals so as to cause the magnetic reluctance to become substantially infinite; the field windings and the armature windings are wound around the parts of the yoke spaced at n equal intervals, the imparting of magnetic effect mutually between the field windings and armature windings being prevented by the existence of parts of narrow width of the yoke; and an inductor having salient poles is rotated thereby to lead out electrically independent outputs from the armature windings has been proposed.
In a generator system of this character, however, since a cylindrical stator iron core, that is, the yoke, has parts of narrow width in the diameter direction, the mechanical strength is low, and a great electromagnetic force arising from vibration of the engine or short circuiting at the time of welding acts on the yoke part. As a consequence, there have been various problems such as the necessity of resorting to a measure to prevent deformation.